1. Field of the Invention
The present invention relates to a liquid ejecting device for delivering liquid droplets onto an object by ejecting the droplets, and an ejection control device for controlling the ejection. In addition, the present invention relates to a liquid ejecting method and program for realizing the liquid ejecting technology, and to a recording medium with the program recorded thereon.
2. Description of the Related Art
One method of representing the grayscale of a printed image is a pulse number modulation method. In this method, the minimum image-constitutional unit, “pixel”, is drawn as a set of small-diameter droplets. The number of droplets determines an apparent pixel diameter forming a pixel. A difference in pixel diameter is recognized as a difference in pixel grayscale. The number of droplets is the number of droplets delivered to a “pixel region” corresponding to one pixel.
FIG. 1A shows an example of an ejection pattern corresponding to a pixel grayscale. The ejection pattern is formed by a string of ejection data items, each indicating whether there is ejection of a droplet. The numeral “1” represents ejection of a droplet, and the numeral “0” represents no ejection of a droplet. In this example of the ejection pattern, one pixel is formed by a maximum of eight droplets. Each numeral in FIG. 1A corresponds to the minimum unit (ejection period) of ejection timing.
The ejection pattern is stored in a buffer memory so as to be associated with a pixel region in which a pixel is to be drawn, and is transferred to a corresponding nozzle (ejecting outlet). At this time, the ejection data items are sequentially read from bit 0 of the buffer memory. Ejection of droplets is controlled based on the ejection pattern. This process of control is shown in FIGS. 1B and 1C.
Liquid ejecting heads include the inkjet printer head disclosed in Japanese Unexamined Patent Application Publication No. 2003-226017. In this head, a plurality of nozzles are arranged in a line. The nozzles are used to simultaneously draw pixels, whose number is equal to the number of nozzles. This type of head is called a “line head”. In this case, ejection patterns as described above are stored in buffer memories, whose number is equal to the number of pixels to be drawn.